Not necessarily a broken spring, could be something jamming the mechanism.

First thing I would do is see if you can manually advance the mechanism. Remove the fader. Switch the lever from MOT to O, and lock the run release to M. Then use the rewind crank in the 1:1 or 8:1 shaft to advance (or rewind) the mechanism. If you don't have a rewind crank use something that will locate in those shafts without damaging them, maybe flat end pliers, or file a slot in the right size tubing and drill a hole in the other end for a rod handle. You might find a tight spot needs to be overcome due to something embedded in gear teeth, or the mechanism was gummed somewhere enough to overpower the spring. If it won't advance easily, don't force it, it will need to be looked at by a repairman. Avoid opening the camera up yourself if the spring is fully wound.

When you say you cranked the camera you mean you wound the spring, no? If so, the spring is not the problem.

I suspect somebody tinkered with the camera, loosened the screw on the T-I lever, and now the stop-start wheel is jammed.

Try to pull it up with the aid of a long M2 screw in there, wiggling the side release button in both directions. Once the axle flush with the guide bush lay the lever on the square top and put the original screw back.

Jumping in on this, I just got a 16H as well but am having a slightly different problem. The front shutter button is sticky to the point where when it's pressed the camera almost runs in M mode and doesn't always disengage cleanly. Other than that it seems to run well. How big of a problem is this and where are good places to get a CLA?

Your camera spring drive may be disengaged from the transport. This is selectable "on" or "off" and enables the film transport to be hand-cranked or rewound for multiple exposure of the film.

Alex. There may be other issues with your camera, so don;t take too much heed of my comment. The Bolex H16 camera family button never starts or stops "cleanly" It is a rather crude mechanical interrupt so you have to be "decisive" when pressing the run button and releasing it, fast not slowly.

To avoid shock-loading the transport when re-engaging the spring drive, best practice is to not switch from "O" to "MOT" with a fully wound spring. The spring rewind crank should be swung open and engaged with the drive, then the tension of the spring taken up very slightly.

Then move the nearby lever from "O" to "MOT". If it does not swing entirely to position, allow the spring rewind lever to unwind just a trace and the drive will engage. You can then release the spring rewind lever and stow it.

Pay heed to better qualified people than myself who may comment here.

If amateurs have visited inside the camera mechanism or sprayed WD40 in through the gaps in the case, the mechanical governor may have become contaminated. It is an old-school centrifugal governor consisting of a brass bell and three small articulated arms with leather shoes. If these shoes have become soaked in WD40 and the light fractions have gassed off, the shoes may have stuck in storage.

Robert comments spot on. I have abstained from the obvious in order to not destroy my image as a behind-the-curtain person. It ain’ wise for a tech to jump into the limelight. I have just finished assembly of a Switar 12,5 mm, f/1.5. There wasn’t weapons dilution 40 sprayed into it but the sulphur contained in the mineral grease had reacted with the copper of the bronze bushes to what is known as copper sulphate, that green blue goo.